Semiconductor memory devices may be classified into volatile memory devices and non-volatile memory devices. Volatile memory devices include DRAM devices and SRAM devices, and non-volatile memory devices include flash memory devices, phase change memory devices, resistance RAM (RRAM) devices, and magnetic RAM (MRAM) devices.
In these memory devices, electronic addressing and/or logic devices used to store and/or process data have been fabricated using inorganic semiconductor materials such as crystalline silicon. While inorganic semiconductor memory devices formed of inorganic semiconductor materials have enjoyed some technical and commercial success, their complex structure may result in increased expense and reduced data storage density. Volatile memory devices formed of inorganic semiconductor materials may require continuous current to maintain stored data, resulting in heat generation and high power consumption. Non-volatile memory devices may have reduced data storage density due to more complex circuit design and may be more costly. Data processing speed may be relatively low and power consumption may be relatively high.
Attempts to apply organic materials to various electronic devices have been made, and some electronic devices (such as thin film transistors, lasers, emission diodes, etc.) successfully employ organic materials. In addition, several organic materials having electrical switching characteristics between two different states may be used as data storage elements of memory devices.
Conventional organic memory devices may include: a single organic material layer; a plurality of organic material layers and a conductive layer such as a metal particle layer between the organic material layers; or an organic compound layer with conductive nano particles dispersed in an organic matrix. An organic memory device using organic material layers with a conductive layer therebetween as a data storage element is disclosed, for example, in U.S. Patent Publication No. 2004/0246770, entitled “Organic Distable Element, Organic Distable Memory Device Using the Same, and Process for Driving the Same”, filed by Kano. The disclosure of U.S. Patent Publication No. 2004/0246770 is hereby incorporated herein in its entirety by reference.
When a single organic material layer is used as a data storage element, however, only a few types of organic material layers may be suitable as data storage elements. Moreover, a single organic material layer may cause degradation of operation characteristics. In addition, when organic material layers with a conductive layer therebetween are used as a data storage element, the conductive layer may be difficult to form, especially a metal particle layer, between the organic material layers. Further, when an organic compound layer is used as a data storage element, distribution of cell characteristics may deteriorate due to segregation of conductive nano particles.